Off‐reef planktivorous reef fishes respond positively to decadal‐scale no‐take marine reserve protection and negatively to benthic habitat change

The effects of no‐take marine reserve (NTMR) protection and changes in benthic habitat on fusiliers (family Caesionidae) were investigated at four small Philippine offshore islands on time scales of 10–31 years. Fusiliers are highly mobile, schooling, medium‐sized planktivorous fish that generally feed “off‐reef.” For these reasons, and given the small size of the NTMRs (3.6–37.5 ha) in this study, it was predicted that fusilier density would be unlikely to show clear effects of NTMR protection, or to respond to changes in benthic habitat. In contrast to predictions, clear NTMR effects were observed on fusilier density at three of the four NTMRs, with durations of protection from 14 to 31 years. Furthermore, the study provided strong evidence that benthic variables, specifically cover of live hard coral and dead substratum, affect the density of fusiliers. This effect of benthic habitat on density was highlighted by several major environmental disturbances that caused shifts in the benthic habitat from live hard coral to dead substratum. For two of the three most abundant species of fusiliers individually, and for all three of them combined (Pterocaesio pisang + Caesio caerulaurea + Pterocaesio digramma/tessellata), as live hard coral cover decreased, fish density decreased. It is hypothesized that these “off‐reef” daytime feeders may have such a strong association with live hard coral cover because they use this habitat as nocturnal sleeping sites. Multivariate analyses indicated that, across all sites and times sampled, cover of live hard coral and dead substratum accounted for 38% of the variation in fish assemblage structure. These results are important as there are very few reports in the published literature of strong effects of NTMR protection or changes in benthic habitat on the density and assemblage structure of fusiliers.     

SCUBA divers above the waterline: Using participatory mapping of coral reef conditions to inform reef management

Coral reefs provide important ecological services such as biodiversity, climate regulation, and cultural benefits through recreation and tourism. However, many of the world's reefs are declining, with Caribbean reefs suffering a significant decline in living corals over the past half century. This situation emphasizes the need to assess and monitor reef conditions using a variety of methods. In this study, a new method for assessing reef conditions to inform management using participatory mapping by coral reef “experts” in the U.S. Virgin Islands (USVI) is described. Occupational SCUBA divers were recruited (n=87) to map coral reef conditions, uses, and threats (stressors) using an internet-based mapping website. The data reveal an uneven geographic distribution of reef conditions in the USVI with the most frequently mapped perceived healthy reef characteristics being: large amount of physical reef structure (n=872 markers); endangered or threatened species present (n=721); and large amount of live coral cover (n=615). The greatest perceived threats were: invasive species (n=606); water pollution (n=234); and unsustainable fishing (n=200). Areas of important reef characteristics, perceived threats to reefs, and perceived recovery potential were plotted to identify areas requiring critical management attention. The authors found that perceptions of healthy reef conditions outnumbered perceptions of reef threats for nine of the ten most familiar coral reefs; the most frequent activity type within the coral reefs was tourism diving; and for the most familiar coral reefs, the divers perceived a high recovery potential. Given the novelty of participatory mapping methods to assess coral reefs, the strengths and weaknesses of the method is evaluated. The authors further propose a management typology for categorizing reef areas to inform their future management. In the absence of primary data, or, as a supplement to underwater surveys and remotely-sensed data on reef condition, participatory mapping can provide a cost-effective means for assessing coral reef conditions while identifying place-specific reef locations requiring management attention.     

基于多波束声呐的人工鱼礁区地形特征分析

建设人工鱼礁(Artificial Reef,AR)是恢复和养护近海渔业资源的重要措施。尽管中国沿海各地人工鱼礁规模宏大,但对于鱼礁投放后的监测明显不足。传统调查方法存在效率低、成本高等缺点,多波束测深系统(Multibeam Echo Sounder,MBES)为探测鱼礁区地形地貌提供了一种有效的技术手段。本文利用高分辨率的多波束测深系统,获取礁区详细的测深数据,快速确定鱼礁位置、形态等信息;应用地形分析工具提取地形变量(坡度、曲率、粗糙度、地形耐用指数及地形起伏度),分析投石后海底地形特征。研究表明,礁石投放后海底地形发生显著变化(水深5~10 m),礁石发生沉降现象(下沉深度约0.45 m),礁石周围出现冲淤地形(礁石堆高1.65 m,影响范围5 m左右)。分析人工鱼礁引起的微地形地貌的变化,可以为鱼礁的监测与效果评估工作提供一种新的技术方法,具有较强的现实意义。     

Borehole image-based evaluation of coral reef porosity distribution characteristics

In this study, we used digital borehole image camera to obtain images of porosity distribution in coral reefs in South China Sea, and developed an effective evaluation system for such distributions. First, the original images are preprocessed, allowing the pore regions to be automatically detected. The depth and sectional functions are established to measure five parameters: pore count, pore radius, radius concentration rate, total pore area ratio, and fractal dimension count. These are used to calculate the characteristic values of porosity distributions, and their fuzzy relationships are used to build the evaluation model, determine the Hamming distances between distributions, and establish the relationships between the characteristics and coral rock classifications. Test results from applying the method on a deep borehole image segment show the results to be consistent with other methods, and the following conclusions can be reached: (1) the porosity evaluation model is a viable way to analyze porosity distribution characteristics; (2) the resulting classification method is viable; and (3) porosity distribution analysis on coral reefs has important implications.     

潮流作用下环礁断面的流动特征研究

本文首先通过循环水槽试验测量分析了正向和反向潮流影响下概化环礁断面的流动特性,试验结果表明：在正向流和反向流作用时,礁坪上仅存在亚临界流,并可观察到经典的壁面有界流动流速剖面特征;沿礁的平均水位与各个测线上的流速随潮流幅值的增大而增大。本文随后采用雷诺平均的Navier-Stokes方程并结合标准的k-ωSST湍流模型建立数值水槽,进一步研究了多种水动力与礁型因素影响下前后礁外礁缘处的流速变化规律。数值模拟结果表明：后礁外礁缘处的平均流速均大于前礁外礁缘处;平均流速随潮流幅值的增大而增大,随礁坪水深、礁坪宽度、潟湖宽度和礁前斜坡坡度的增大而减小;最后基于数值模拟结果提出了预测各种因素影响下前后礁外礁缘处流速的幂函数型经验公式。     

南沙群岛海底地貌制图研究——以1∶100万郑和群礁幅为例

中国海域辽阔,但公开发表和出版的1∶100万及更大比例尺的海底地貌图尚属空白。在综合研究已有的海底地貌分类系统的基础上,以南沙群岛郑和群礁幅为实验区,尝试建立了该海区1∶100万海洋地貌分类系统,利用历年来南沙群岛海区等深线图(1∶50万)、沉积图(1∶200万)、地质地球物理图集(1∶100万)及各种文献资料和在专家指导的基础上,绘制了该幅的海底地貌图并对该区域的地貌格局进行了分析。实验表明,通过对现有资料的综合进行1∶100万海底地貌制图是可行的。实验发现:1)等深线数据如同陆地上的等高线数据,是进行海底地貌制图的基本和主要数据源;2)海底底质和沉积物数据是进行海底地貌成因类型判别的重要依据;3)海底构造格局对海底地貌格局起着根本的控制作用,因此海底地质地球物理数据也是进行海底地貌制图不可或缺的数据之一。     

印太交汇区海洋鱼类多样性格局与演化研究进展

印太交汇区不仅是热带物理海洋海气能量汇聚中心、地质板块活跃中心以及生物多样性中心,而且也是用于开展地球系统物质能量交换与全球气候变化以及海洋生物多样性起源研究的理想靶区,因此一直受到世界科学家们的广泛关注.作为全球34个生物多样性热点区域之一,印太交汇区的珊瑚礁三角区孕育了全球76％的造礁珊瑚、75％的红树林、50％的...     

南海珊瑚礁海域黑缘尾九棘鲈生物学特征初步研究

根据2018—2019年在南沙群岛和西沙群岛珊瑚礁海域采集的礁栖鱼类黑缘尾九棘鲈(Cephalopholis spiloparaea)样本, 对其群体结构、性腺成熟度、摄食强度、肥满度、年龄与生长等生物学特征进行了初步研究, 通过对比分析了南海这两个珊瑚礁海域中黑缘尾九棘鲈生物学特征的地理差异。结果表明: 在南沙海域和西沙海域中黑缘尾九棘鲈的平均体长分别为105.5±10.5mm和110.4±13.1mm, 两海域间的体长和体质量分布均具有极显著的差异(P<0.01); 南沙海域与西沙海域样本体长和体质量关系的异速生长因子b值分别为2.881与2.797; 耳石样本分析结果显示年龄范围为0.58~1.44a, 两个海域间并无显著性差异(P>0.05); 由von Bertalanffy生长方程计算所得的生长参数显示, 南沙海域的黑缘尾九棘鲈比西沙海域的体型相对较小、生长速度相对较快; 两海域黑缘尾九棘鲈的性腺成熟度均以Ⅱ期为主, 且西沙海域样本性腺成熟比例高于南沙海域; 摄食等级以1级为主, 两个海域间的摄食等级分布无显著性差异(P>0.05); 与西沙群岛海域相比, 南沙群岛海域的黑缘尾九棘鲈群体表现出肝体比较低的特征。     

珊瑚礁生态修复效果评价指标体系研究进展

近年来气候变化和人类活动导致全球范围内珊瑚礁大幅度退化,珊瑚礁生态系统面临严重威胁.开展珊瑚礁生态修复是恢复珊瑚礁生态系统最有效、最根本的措施之一,它不仅可以恢复珊瑚礁在生态系统中的功能,还可以提供相应的社会、文化、经济效益以及服务价值.近十几年来,我国在海南、西沙以及广西等海域开展了大量的珊瑚礁生态修复实践,但在评价...     

烟台近岸人工鱼礁与自然岩礁底层渔业生物群落特征对比分析

为探究烟台近岸人工鱼礁区的底层渔业群落与自然岩礁区的差异,本研究于2018年5月—2019年2月在位于山东烟台近岸的养马岛自然岩礁区、牟平人工鱼礁区及毗邻泥沙区开展4个季度的渔业调查.调查共发现渔业生物15目37科53种,自然岩礁区与人工鱼礁区的平均物种数的差异不显著,但均明显高于泥沙区(Kruskal-Wallis ...